GSH attenuates RANKL-induced osteoclast formation in vitro and LPS-induced bone loss in vivo
BIOMEDICINE & PHARMACOTHERAPY
Authors: Han, Bing; Geng, Huan; Liu, Liang; Wu, Zhixin; Wang, Yizhong
Abstract
Osteoclasts are capable of adhering the bone matrix, then secrete acid and lyric enzymes to resorb it. Reactive oxygen species (ROS), as a signaling messenger, plays an important role in the receptor activator nuclear factor kappa B ligand (RANKL) signal pathway during osteoclast differentiation. Glutathione (GSH) is known to be a powerful antioxidant which can scavenge intracellular ROS. This study aimed to investigate whether GSH can as a protective agent against the RANKL-stimulated osteoclastogenesis by suppressing intracellular ROS. Here, we showed that GSH markedly restricted RNAKL-induced differentiation of bone marrow-derived macrophages (BMMs) to form osteoclasts. GSH suppressed RANKL-induced ROS generation and subsequent ROS-induced NF-kappa B signaling pathways within BMMs during osteoclastogenesis. Further, GSH acted to significantly downregulate the osteoclastogenic genes expression of nuclear factor in activated T cells, cytoplasmic1 (NFATc1), C-fos, the tartrate-resistant acid phosphatase (TRAP), and osteoclast-associated immunoglobulin-like receptor (OSCAR). Our results suggested that GSH inhibits intracellular ROS-mediated NF-kappa B signal pathway involved in osteoclast differentiation. These findings might form the basis of a new strategy for treating bone disease associated with excessive bone resorption.
Dual Switch Mechanism of Erythropoietin as an Antiapoptotic and Pro-Angiogenic Determinant in the Retina
ACS OMEGA
Authors: Samson, Faith Pwaniyibo; He, Weilue; Sripathi, Srinivas R.; Patrick, Ambrose Teru; Madu, Joshua; Chung, Hyewon; Frost, Megan C.; Jee, Donghyun; Gutsaeva, Diana R.; Jahng, Wan Jin
Abstract
Constant or intense light degenerates the retina and retinal pigment epithelial cells. Light generates reactive oxygen species and nitric oxide leading to initial reactions of retinal degeneration. Apoptosis is the primary mechanism of abnormal death of photoreceptors, retinal ganglion cells, or retinal pigment epithelium (RPE) in degenerative retinal diseases, including diabetic retinopathy and age-related macular degeneration. The current study evaluated the function of erythropoietin (EPO) on angiogenesis and apoptosis in the retina and RPE under oxidative stress. We determined the pro-angiogenic and antiapoptotic mechanism of EPO under stress conditions using a conditional EPO knockdown model using siRNA, EPO addition, proteomics, immunocytochemistry, and bioinformatic analysis. Our studies verified that EPO protected retinal cells from light-, hypoxia-, hyperoxia-, and hydrogen peroxide-induced apoptosis through caspase inhibition, whereas up-regulated angiogenic reactions through vascular endothelial growth factor (VEGF) and angiotensin pathway. We demonstrated that the EPO expression in the retina and subsequent serine/threonine/tyrosine kinase phosphorylations might be linked to oxidative stress response tightly to determining angiogenesis and apoptosis. Neuroprotective roles of EPO may involve the balance between antiapoptotic and proangiogenic signaling molecules, including BCL-xL, c-FOS, caspase-3, nitric oxide, angiotensin, and VEGF receptor. Our data indicate a new therapeutic application of EPO toward retinal degeneration based on the dual roles in apoptosis and angiogenesis at the molecular level under oxidative stress.